hey, welcome to 12tone building blocks, our monthly series about the fundamentals of music
theory.
we've already covered scales, keys, and chords, but for the most part, we've only talked about
them as separate ideas.
in practice, though, they're all deeply related.
after all, chords are built out of notes, keys tell us which notes we're allowed to
use, and scales tell us how those notes are going to feel, which gives us a pretty good
idea of what to expect from chords that include them.
each scale and each key has a specific set of chords that goes along with it.
for instance, F major (bang) has these (bang) but, well, how do we know that?
finding the right chords for a scale is called harmonizing, and it's actually pretty simple.
we pick a starting note, like this F, skip the next note, then include the third one,
A, skip the fourth, and then add the fifth, C, on top.
because of the way normal scales are arranged, taking every other note like this will always
create some kind of triad, in this case F major.
(bang) if we repeat this alternating process for every possible starting note in the scale,
and we wind up with this, (bang) a fully harmonized major scale.
and if we want to get extra fancy, we can add a seventh on top, making this.
(bang)
of course, no matter where you start your scale, you'll always get the same pattern
of chords, and it's often useful to describe them not in terms of their actual roots, but
their relationship to the key.
for instance, the keys of F major, G major, and C major all have A minor triads in them,
but the way the chord feels is different in each one.
that's where roman numeral analysis comes in, and it's as simple as it is game-changing:
all you have to do is take the chord symbol and replace the note name with the roman numeral
representing the scale degree it's built on.
for instance, in F major, the A minor chord is built on the third note in the scale, so
we'd write it as IIImi.
on the other hand, in C major, it's built on the sixth note, so we call it VImi even
though it's the same underlying chord.
as a brief aside, this notation definitely isn't universal: there's a couple different
schools of thought on how best to approach it.
they're all pretty similar, but many people prefer to show minor triads by writing the
roman numerals in lowercase, so our A minor would just be iii.
I don't use that system, but you'll definitely encounter it at some point so you should probably
know what it means.
also, for me, the roman numerals always represent the note's position in the major scale, so
if you're using a different scale with different intervals, you show that change by adding
a sharp or flat in front of the number.
so in F minor, Ab major would be the bIII chord, because its root is a half step lower
than the major scale's third degree.
that, again, is not universal, though.
it's just how I was taught.
(NOTE TO REVIEWERS: I kinda struggled with making this part clear.
does it make sense, or do I need to work on it more?)
anyway, back to chords, there's one more thing we need to talk about: chord functions.
modern music theory is built on the idea that different chords in a key behave differently,
based on what notes they contain and how those notes interact.
this is called functional harmony, and we tend to break the chords into three main groups.
the first is called tonic function.
these are chords that feel like they're at rest.
they're often called home chords, and they're incredibly stable.
this includes the I chord (bang) as well as the VI minor chord (bang) and, normally, the
III minor chord.
(bang) an easy way to remember this is that they're the three triads that contain the
third degree of the scale, which is probably the most important note for defining the scale's
overall sound.
the second group is called dominant function.
these are unstable chords that point you back to the tonic, and they're the main engine
that drives songs forward.
these include the V chord (bang) and the VII diminished, (bang) which both contain the
seventh degree of the scale.
this is a half step below the root, and it has such a powerful pull upward that theorists
often call it the leading tone.
dominant function chords also often include the fourth degree of the scale which, combined
with the leading tone, creates a tritone, (bang) a very unstable interval that makes
the whole chord want to collapse.
(bang)
the third group is the subdominant function chords, including the IV chord (bang) and
the II minor.
(bang) these serve as a sort of bridge between the other two functions: they're a bit unstable,
containing the fourth degree, which wants to fall back down to the third, but they don't
have a leading tone, so they're not nearly as directional as dominant function.
these take you away from home, but they don't point you back yet.
that's not their job.
the idea of chord functions is critical to our modern understanding of harmony, but it
does have its problems.
for instance, since dominant function is so dependant on the leading tone, it doesn't
work in scales that have a lowered seventh degree, like natural minor.
in fact, a lot of these functions get way more subjective when we stray from the major
scale, but still, it's one of the best frameworks out there for explaining most contemporary
music, and that's gotta be worth something.
anyway, thanks for watching!
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